20402791 has 4 divisors (see below), whose sum is σ = 20422584. Its totient is φ = 20383000.

The previous prime is 20402761. The next prime is 20402797. The reversal of 20402791 is 19720402.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 20402791 - 2⁷ = 20402663 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (20402797) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8260 + ... + 10441.

It is an arithmetic number, because the mean of its divisors is an integer number (5105646).

Almost surely, 2^20402791 is an apocalyptic number.

20402791 is a deficient number, since it is larger than the sum of its proper divisors (19793).

20402791 is a wasteful number, since it uses less digits than its factorization.

20402791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19792.

The product of its (nonzero) digits is 1008, while the sum is 25.

The square root of 20402791 is about 4516.9448745806. The cubic root of 20402791 is about 273.2519020099.

The spelling of 20402791 in words is "twenty million, four hundred two thousand, seven hundred ninety-one".